1. Field of the Invention
The present invention concerns a portable timepiece such as wristwatch and pocket watch, and especially relates to a portable timepiece in which a bezel is rotatably attached to a case band.
2. Description of the Prior Art
The bezel rotatably attached to the case band of the portable timepiece can exhibit various functions by rotating it to be set to an optional position, and can contribute to increase 1n additive value of the portable timepiece.
Heretofore, there is known a wristwatch in which, in order to rotatably attach the bezel to the case band, a step part, to whose inner periphery there is attached a cover glass, is formed in an upper part outer periphery of the case band over its whole periphery, an annular protrusion is formed in an outer periphery of the step part, a protrusion which is formed in an inner periphery of the bezel rotatably fitted to the step part of the case band is engaged from below with the protrusion of the step part outer periphery part to thereby prevent the bezel from disengaging, and an O-ring is interposed between the bezel and the step part (refer to JP-A-10-239454 Gazette (paragraphs 0002–0005, FIG. 19–FIG. 23)).
In a constitution of the JP-A-10-239454 Gazette, since the O-ring is interposed between the bezel and the step part in order to smoothly rotate the bezel, it is easy to rotation-operate the bezel to a desired position. However, as to the bezel capable of being simply rotation-operated, since its force holding a stationary state with respect to the case band is weak, it is easy that the bezel is carelessly deviated from a rotated position set by a user with effort to a position not desired by the user by an unexpected external factor and a chance.
In view of this point, in a case where a frictional resistance force is increased by strengthening a gripping force of the O-ring, the careless or unintended rotation of the bezel can be suppressed. However, reversely to this, in a case where the user rotates the bezel, the rotation of the bezel becomes difficult and thus an operability becomes deteriorated.
The problem to be solved by the present invention is to provide a portable timepiece capable of suppressing the fact that the bezel is carelessly rotated and deviated, without impairing the rotation operability of the bezel.